GB-A-1511935 describes a strippable coating system comprising a non-crosslinked polyamide intermediate coating between the primer and the top coat. This at least partially resists the solvent used to remove the top coat and can itself easily be removed by alcohol-based solvents to reveal the primer. DE-A-2528943 describes a linear non-crosslinked elastic polyurethane coating used between crosslinked polyurethane primer and top coat layers. EP-A-147984 describes a barrier intermediate coating comprising a film-forming addition polymer comprising units of a vinyl aromatic monomer and units of a monomer containing a hydroxy alkyl group in an amount to provide a hydroxyl content of the addition polymer in the range 0.5 to 5 per cent by weight reacted with a polyisocyanate containing at least 2 isocyanate groups per molecule.
WO-A-98/13148 describes a process for overcoating a substrate having a cured primer coating with a curable top coat which when cured is swellable by a stripping composition, in which process a non-volatile polar material having high affinity for the primer surface is applied to the primed substrate from an aqueous liquid vehicle before coating with the top coat, whereby the said polar material facilitates the removal of the top coat from the primer by the stripping composition.
EP-A-14597 describes a paint undercoat in which the film-forming resin has an acid value of from 10 to 45 mg KOH/g. Paint films including such an undercoat are stripped by means of a paint stripper having a pH of from 8 to 14 which attacks the undercoat paint film.